Queries for the spring/washer technicians, following work to Mk3

[andrewM]

Lacking a chrono, I find that old Eley Wasps fired against a flat pellet-catcher (inserted paper prevents rebounds) provide a guide as to the power of a rifle, determined by the flatness of the pellet.

Louis Van Hovell, from this site, very kindly sent me three steel washers/spacers of approx. 1mm each. This is because one of my two Mk3s displayed power that appeared sub-optimal, evidenced by pellets where their centres were well raised above their surrounds, after firing into the pellet-catcher.

After placing merely one greased washer inside the piston, the situation changed. This time, the pellets were flattened throughout - including the centre.

In a another development, some months ago I bought an old unused Mk3 spring from a BBS member. I noticed this was between 1 - 1.5cms longer than my existing Mk3 spring (I should have measured both but overlooked this before re-assembling the rifle). Given it was something of a task to screw the trigger unit back into the cylinder, because of pre-load of the unused spring, I experimented instead with a single washer - which appeared to have the desired effect.

Questions:

1 I did not expect a single washer, about 1mm wide, to have such an effect. How can this be? What are the mechanics at work here?

2 Would additional washers, either in the piston or at the trigger end, have an equal added impact? It seems I have already achieved my objective with merely one washer but I presume additional washers would produce a further boost or would there be a diminishing return?

3 Would the longer spring have had a similar outcome? Does a longer spring (assuming the power of the spring is similar on a per cm basis) raise the power of a rifle? This sounds obvious but I recall reading on this site that a longer spring does not necessarily raise the power and can diminish it.

4 Finally, given the existing spring within the rifle is some 1 - 1.5cms shorter than the unused spring, I am presuming that this has occurred over a period of some 46 years, due both to the use of the rifle over this time frame and the pre-load within the rifle. Would this be a reasonable assessment?

Whilst the above refers to a Mk3, the questions would appear relevant to other rifles.

Rgds to all
A

[rancidtom]

Just buy a chrono, you can read plenty of books, articles in magazines and on t'internet as to the mechanics and physics involved, starting a discussion here will no doubt provide you with many conflicting bits of advice and conjecture from many people, some of it will be fact and some will be myths being repeated by people who have no way (or possibly no interest) in proving or disproving the myths they have heard and go on to repeat, just like "the bloke down the pub".
Chrono's are quite cheap and then you know what your rifle is doing with whatever pellet rather than keeping your fingers crossed and doing uncalibrated tests as to "how many pages of a phone book" the pellet will penetrate or how flat it is when fired against something. You also know that your rifle is legal if you need it to be sub12 FtLb or for instance sub6 if used for certain competitions (certain bell target leagues and the Scouts only allow sub6).

[laverdabru]

I always used to think a springer was the simplest thing ever. But like simple 2-stroke motorcycle engines, very basic alterations can make a big difference to the power output. Not always for the best, as far as reliability is concerned.
Nowadays, I just buy something with the power required rather than p'about & possibly ruin a nice, original gun/motorbike.

[andrewM]

Yes, seeking a chrono is on my list but not a priority.

The output was poor - probably because the spring was somewhat compressed after 45+ years - but now seems closer to where it should be, ie closer to 10ft/lbs, as a result of the action taken.

The mechanics of what are fairly simple alterations fascinate me, so I thought I would request the views of the technical people, here, who know about such things. That said, I would never contemplate complex alterations, such as playing around with the transfer port; the technical aspects of that are sufficient for a Phd!

[bill57]

RancidTom is right. You say getting a chrono is not a priority, but if you like tinkering with springers it should be. Otherwise it's all guesswork, and you can never draw any conclusions from your investigations.

[vbull]

Most important young you can have is a chrono, bought a tiny little fully portable Air Force One I think it's called a while back, artificial light, instant accurate readings makes the whole subject even more fascinating. If you're into this sort of thing best £100 or whatever it was you'll spend for a while IMHO.